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Bug 555094

Summary: sys-apps/rng-tools: man page reports misleading default value for --fill-watermark
Product: Gentoo Linux Reporter: Göktürk Yüksek <gokturk>
Component: Current packagesAssignee: Gentoo's Team for Core System packages <base-system>
Status: RESOLVED FIXED    
Severity: normal    
Priority: Normal    
Version: unspecified   
Hardware: All   
OS: Linux   
Whiteboard:
Package list:
Runtime testing required: ---
Attachments: Proposed fix for manpage
Patch for the ebuilds
Patch manpage inside ebuild with sed

Description Göktürk Yüksek archtester gentoo-dev 2015-07-16 16:51:40 UTC 
According to rngd man page the default value for the '--fill-watermark' option is 2048 bits. However, upon examining default_watermark() function in rngd_linux.c, it turns out that this is true for systems where poolsize cannot be obtained. In linux, the pool size can be obtained by reading '/proc/sys/kernel/random/poolsize'. If rngd is capable of reading the proc entry, as it should be, then it sets the --fill-watermark value to be 75% of the total pool size, typically 3072 bits.

Gentoo mitigates this problem by explicitly specifying the '--fill'watermark 2048' in the init script. Still, it is ambiguous which is the intended default value (2048 or 3072 bits), and which one Gentoo should provide by default.


Reproducible: Always
Comment 1 Göktürk Yüksek archtester gentoo-dev 2015-07-17 01:48:40 UTC 
Created attachment 406954 [details, diff]
Proposed fix for manpage

For reference purposes:
- Suse uses 3700 bits for watermark
- Debian uses 50%
- Fedora goes with the default 75%

There doesn't seem to be any consensus on the default value. I suggest that we modify the manpage to reflect the correct behaviour and leave the default 2048 bits provided by the init script as is.
Comment 2 Göktürk Yüksek archtester gentoo-dev 2015-07-17 01:49:16 UTC 
Created attachment 406956 [details, diff]
Patch for the ebuilds
Comment 3 Göktürk Yüksek archtester gentoo-dev 2015-07-21 15:56:59 UTC 
Created attachment 407350 [details, diff]
Patch manpage inside ebuild with sed

As per our discussion on #gentoo-proxy-maint with idella4, patching the manpage with sed is better than creating a separate patch file. It takes up less space than the patch file and easier to read when it's inside the ebuild. Note that this is only for rng-tools-5, although it should apply the same way to rng-tools-4 too. There is a stabilization bug open for rng-tools-5, so it makes sense to patch only rng-tools-5 and get rid of rng-tools-4 as soon as possible.